/Engine/Source/Runtime/Engine/Classes/Engine/AssetManager.h
Scans a list of paths and reads asset data for all primary assets of a specific type. If done in the editor it will load the data off disk, in cooked games it will load out of the asset registry cache
Number of primary assets found
virtual int32 ScanPathsForPrimaryAssets ( [FPrimaryAssetType](API\Runtime\CoreUObject\UObject\FPrimaryAssetType) PrimaryAssetType, const [TArray](API\Runtime\Core\Containers\TArray)< [FString](API\Runtime\Core\Containers\FString) > & Paths, [UClass](API\Runtime\CoreUObject\UObject\UClass) * BaseClass, bool bHasBlueprintClasses, bool bIsEditorOnly, bool bForceSynchronousScan )